THE ACTION OF PROGESTIN ON THE UTERUS OF THE CAT

¹ The National Institute for Medical Research, London, N.W. 3, and the Department of Physiology and Pharmacology, University of Alberta, Edmonton, Canada

In the immature and also in the ovariectomised adult cat strone causes the development of the long, straight endometrial glands, possessing a distinct lumen, bordered by a columnar epithelium. Following the administration of progestin, these glands hypertrophy and become greatly twisted. At a later stage their mouths open, giving the mucosa the fringed appearance seen in normal pseudo-pregnancy in the cat [Gros, 1933]. In the hypophysectomised cat the amount of progesterone required to evoke these changes appears to be somewhat greater than in the ovariectomised animal. Compared with the rabbit, the amount of strone required to sensitise the uterus to progestin is about seventy times as great.

Considerable alveolar development of the mammary glands simultaneously occurs in the ovariectomised cat, but no effect was noticed in the mammary gland of a hypophysectomised cat.

The authors wish to express their gratitude to Dr. A. S. Parkes, F.R.S., for his advice and interest in this work, and also to Dr. R. K. Callow for the crystalline progesterone. One of us (M. K. McP.) wishes to thank Sir Henry Dale, F.R.S., for the hospitality and facilities of the National Institute for Medical Research.